Articulated floating structure

ABSTRACT

The invention relates to the design of floating structures for the installation of equipments such as wind turbines and solar power plants.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional application No. 60/922,397 filed on Apr. 9, 2007, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The growing demand for energy and the problems related to oil supply have called for new solutions among energy supply technologies. In particular, environmentally friendly energy sources are considered with great attention for the general environmental concerns. Among the green energy sources wind energy has been the world's fastest growing source. In particular offshore wind has emerged as a promising renewable energy resource. However development of offshore wind farming has been restrained by the prohibitive cost of the installations. The invention relates to the design of a floating platform which is expected to be less expensive than current approaches.

Current approaches in the design of floating platform include mainly floating bodies anchored to the sea bottom. The anchoring is usually done with anchors and cables in amount adequate to minimize the movement of the platform. The anchoring line can eventually be under tension (in this case the platforms are called tension leg platforms). The current floating platform technology has been developed mainly for design and construction of offshore oil platforms.

SUMMARY OF THE INVENTION

Aspects of the invention are related to the design of floating structure for the installation of equipment such as wind turbines and/or other energy generation systems (e.g. photovoltaic systems).

The novelty of the design of the floating structure lies in the fact that the structure is composed essentially by two articulated parts. The first part is a floating unit that provides the majority of the buoyancy needed to support the entire structure. The second part is a slender part that mainly supports the equipment that needs to be carried. The parts are connected through the use of a joint that allows reciprocal rotation but not translation (for instance a joint such as gimbals). The slender part has a portion under water connected to a ballast and a portion outside used to support the equipment or parts of it. When the floating platform is placed in water the slender part will be upright due to the presence of the ballast.

The advantage of the design is that under wave attack the part of the structure providing buoyancy will move but because of the type of joint with the slender part it will not transmit rotations. The slender part will be subjected to limited loads by the waves due to its particular shape and will tend to be upright because of the presence of the ballast. Such a kind of floating structure by virtue of its design is expected to be less expensive than the design approaches currently used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Drawing of an embodiment of the invention

FIG. 2: Example of installation of the invention

FIG. 3: Example of alternative use of the invention

FIG. 4: Details of a possible connection between parts of the invention

FIG. 5: Details of a possible joint among parts of the invention

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows and example of an embodiment of the invention. The system in FIG. 1 is composed of a floating part (4), having the shape of a torus. Said floating part can have any other shape as long as it is able to support, exploiting its buoyancy, a relevant part of the weight of the overall structure.

Part 3 represents the slender part supporting the equipment. In FIG. 1 the equipment is represented by a wind turbine with body represented by 1 and propeller represented by 2. Possible equipments range from wind power generators to measurement instrumentation and photovoltaic cells.

The slender part 3 can be made of any suitable material adequate for the loads and the environment of placement of the system. The column 3 can be made as a hallow tube or as a truss structure or in any other way suitable for the design requirement of the specific installation. Column 3 has a part underwater and a part above water. The part underwater supports the equipment of choice, the part underwater is connected to a ballast 7.

The slender part 3 and the floating part 4 are connect with elements that allow to have a connection among them that allows rotation of the slender element 3 with respect to the floating part 4 but not reciprocal translation.

In the embodiment of FIG. 1, the slender element 3 is rigidly connected to part 6. Part 6 is a cantilever element that can rotate with respect to the element 5 about an horizontal axis (say axis A). Element 5 can rotate with respect to the floating part 4 about an axis that is horizontal and orthogonal to axis A.

The connections between element 6 and 5 and the connection between element and the floating part 3 are kind of connections that allow rotation about one axis and prevent translations or rotation about other axes. FIG. 4 shows a detail of a possible way to connect element 5 with element 6. In the figure part 5 a, a cylindrical hole within part 5, houses element 6 in such a way that element 6 is free to rotate with respect to part 5.

FIG. 5 and FIG. 6 show two examples of connection between element 5 and 6 or between element 4 and 5. In FIG. 5, in case of the joint between 5 and 6, 12 represents 6 and 11 represents 5. In case of the joint between 4 and 5, 12 represents 5 and 11 represents 4. In FIG. 5 part 12 can rotate with respect to part 11 because part 12 lies into a cylindrical hole built into part 11. The hole has diameter larger than the diameter of part 12. In FIG. 6 the rotation of part 12 with respect to part 11 is helped by the presence of a ball bearing joint 13.

FIG. 2 shows an example of installation of the invention. 11 represents the free surface of the body of water where the invention is installed. The invention is anchored to the bottom via, at least, a cable 14. The cable is attached to the sea bottom with and anchor or heavy body 10 or any other adequate mean. The mooring line may be equipped with one or more weight, as 9, or springs at some point between the sea surface and the sea bottom to avoid impulsive loading of the mooring line.

FIG. 3 shows another embodiment of the invention in witch a photovoltaic type of equipment is installed on top of column 3

The size of the floating part 4, of the column 3, of the ballast 7 and all the other components is variable, it depends on the needs of the design for the specific installation ( for instance loads, sea state characteristics at the location of installation, etc) and the specific selected type of equipment.

Fins can be built in parts of the invention to improve its stability and/or dynamical behavior

If needed by design consideration parts of the needed equipment can be installed in other parts of the invention itself. For instance in the case of a wind power generator, the gear box and the blades can be located on top of the column 3 and the generator inside column 3. Control mechanisms or electronics could be installed inside the floating body 4. 

1) A floating structure having a. at least one floating body that provides mainly, but not exclusively, required buoyancy for the overall structure to float. b. at least one body having mainly but not exclusively a support function for equipment to be held by the floating structure. Said floating structure having these two bodies connect in such a way that rotations and no translation are allowed between them. 2) The structure of claim 1 where the equipment is a power generation system. 3) The structure of claim 1 where the equipment is a measurement system 4) The structure of clam 1 where the equipment is a telecommunication system 